Non-Invasive Ventilation

Non-Invasive Ventilation

• Pilbeam Chapter 19

Overview of Non-Invasive Ventilation

• One of the earliest forms of mechanical ventilation.
• Negative pressure ventilation
  • Indications, advantages, disadvantages.
• Positive pressure ventilation
  • Indications, advantages, disadvantages.

Goals and Types

• Goals, pathology-specific applications.
• Types of non-invasive ventilator
  • Critical care vs. chronic and homecare use.
• Types of interface
  • Types, advantages and disadvantages.

History and Use of Non-Invasive Ventilation

• Before 1960’s almost all mechanical ventilation was non- invasive.
• Researchers discovered survival rate was higher with Invasive ventilation.
• Invasive ventilation became the standard.
• However, invasive ventilation is associated with higher risk and higher costs.

Improvements and Applications

• Non-invasive methods and approaches have improved.
• Evidence now shows that early and appropriate application of NIPPV can reduce the need for invasive ventilation and the associated risks.
• NIPPV can be delivered by a variety of application interfaces.

Negative Pressure Ventilation

• Use peaked in 1950’s – Polio epidemic, (body ventilators.)
• Inspiration – lung volumes increased by intermittent application of negative pressure to entire body below neck or just to thorax. Negative pressure transmitted across chest wall into pleural space, (transpulmonary pressure.)

Mechanism of Negative Pressure Ventilation

• Exhalation – as negative pressure is released, elastic recoil of chest wall causes passive exhalation.
• Iron Lung – first successful negative pressure ventilator. Consisted of a large metal cylinder. It enclosed patient’s entire body below airtight rubber seal at patient’s neck.
• Designed by Drs. Drinker and Mckhann.

Abdominal Displacement Ventilation

• An alternative during the polio epidemic.
• Also used to help wean from the iron-lung.
• Two forms existed: the “Rocking Bed,” and the “Intermittent Abdominal Pressure Ventilator, (Pneumobelt.)

Positive Pressure Ventilation

• Can be traced back as far as 1780 when first type of bag and mask were used for resuscitation.
• PPV first used with mask in 1940’s.
• IPPV later used to treat acute respiratory failure, complicated by COPD and Asthma.
• Invasive airways and volume ventilators developed in 1960’s.

NIPPV and IPPB

• IPPB – used with a mouthpiece or mask. Became less of a means for ventilatory assistance, and more of a way to deliver aerosolized medications.
• In the 1980’s evidence began to diminish the value of the overwhelming number of IPPB treatments being ordered, and the therapy began a decline in popularity.

CPAP

• CPAP – in the 1980’s CPAP became very effective in treating OSAS.
• Low Levels of continuous pressure act as a pneumatic splint preventing airway collapse or obstruction during sleep.
• Success stimulated production of a variety of devices and interfaces.

Goals of NPPV

• Indications and goals are based on specific pathologic condition, setting and degree of illness.
• Acute Care Setting – NPPV can be lifesaving in acute respiratory failure.
• Benefits of NPPV over invasive – the greatest benefit is the avoidance of intubation.
• In appropriately selected patients, NPPV can be just as effective as invasive ventilation.

Acute Care Applications

• Acute exacerbation of COPD
• Asthma
• Hypoxemic Respiratory Failure/ARDS
• Community-Acquired Pneumonia
• Cardiogenic Pulmonary Edema

Acute Exacerbation of COPD

• Acute Exacerbation of COPD – increased RAW causes an increased demand placed on the muscles of ventilation, which leads to increased O_2 consumption.
• Increasing VE to meet the increased demand, worsens air-trapping which increases RAW, perpetuating a vicious cycle.
• Patient eventually fatigues and respiratory insufficiency becomes respiratory failure.

Asthma and NIV

• Evidence is inconclusive
• However, patients with “Status-Asthmaticus” complicated by CO_2 retention may benefit from NIV
  • Improved gas exchange
  • Decreased PaCO_2
  • Rapid improvement in 1st 2 hrs
  • Improved response to beta-2 with NIV

Hypoxemic Respiratory Failure/ARDS

• Evidence inconsistent
• Wide variety of pathologies
• PaO2/FIO2 < 200, RR > 35
• NIV combined with traditional medical care significantly improved gas exchange, reduced need for invasive vent. and reduced mortality.

Community-Acquired Pneumonia

• Least favorable outcomes
• Some success and evidence of reduced hospital stay and mortality with NIV.
• Better outcomes with subgroup of pts with COPD.
• However, 66% required intubation
• Contraindicated in the presence of excessive secretions.

Cardiogenic Pulmonary Edema

• Mask CPAP effectively used for many years to treat ACPE.
• Patient not responding to traditional pharm. therapy and O_2 therapy, mask CPAP helps.
• Improved oxygenation, increased FRC, increased lung compliance and reduced WOB…

Chronic or Homecare Applications

• OSAS
• Nocturnal hypoventilation syndrome
• Restrictive disorders
• Chronic neuromuscular conditions
• Chronic stable COPD

Other Indications

• Facilitation of Weaning from Invasive Ventilation
• DNI Status

Equipment Selection For NIV

• Acute Care Ventilators
• Home Care Ventilators
• Portable pressure-targeted Ventilators (BIPAP/CPAP) machines

Patient Interface Selection

• Nasal Interfaces
• Full-face (Oronasal) Interface
• Total Face and Helmet Interfaces
• Oral Interfaces

Nasal Masks

• Advantages
  • easy to fit quickly,
  • less risk of claustrophobia,
  • lower risk of aspiration,
  • patient can cough and speak,
  • less mechanical dead space
• Disadvantages
  • Mouth Leaks
  • Eye and facial skin irritation
  • Ulceration over bridge of nose
  • Oral and nasal dryness, nasal congestion
  • Increased resistance through nasal passages

Full-Face (Oronasal) Masks

• Advantages
  • Reduces air leakage through mouth
  • Less airway resistance
• Disadvantages
  • Increased risk for aspiration especially at pressures greater than 20 cm H_2O
  • Increased risk for asphyxia
  • Increased dead space
  • Claustrophobia
  • Difficult to secure and fit
  • Facial irritation/ulceration
  • Must remove to speak or expectorate secretions

Total Face Mask and Helmet

• Total Face Mask
  • Seals perimeter of the face and does not obstruct vision
  • Air circulates throughout entire mask making breathing more comfortable
  • Decreases the incidence of pressure sores
  • Same concerns as full-face mask
• Helmet
  • Transparent PVC cylinder that fits over patient’s entire head
  • Secured by metal ring, silicone collar and straps under each armpit.
  • Not currently FDA approved for use in U.S.

Patient Interface Selection – Considerations

• Emergency/Critical Care
  • Patients tend to have increased shortness of breath.
  • Full-face mask is recommended. However, patient must be observed for potential risk of aspiration.
• Chronic or Homecare
  • a variety of interfaces: nasal mask, nasal prongs or pillows.

Setup and Preparation

• Patient sitting up or at least Semi-fowler’s position.
• Fully explain NIV to patient, procedure, goals, possible complications.
• Determine correct mask type for patient.
• Use sizing template to choose correct mask size.
• Setup and attach mask to ventilator, turn on vent and adjust settings.
• Hold or allow patient to hold mask gently to face while adjusting straps. Adjust straps evenly and avoid over-tightening.
• Talk to and encourage patient. Patient refusal or non-compliance is a contraindication.
• Monitor vital signs and obtain ABG within 1 hour.

Improving Oxygenation

• Increase FIO_2
• Increase CPAP or EPAP
• If on BIPAP, you may also need to increase the IPAP to maintain the pressure support level.
• If airway secretions are an issue, consider interface type and encourage occasional coughing to clear secretions.
• If bronchospasm is present, administer nebulizer therapy.

Improving Ventilation

• In BIPAP, the delta-P or change in pressure supports spontaneous ventilation.
• To increase ventilatory support, that difference must be increased.
• This is most often accomplished by increasing the IPAP
• Also, since this is spontaneous ventilatory support, a patient’s respiratory rate is also important.
• If bronchospasm is present, provide nebulizer therapy.

NIV Failure

• Worsening pH and PaCO_2
• Persistent tachypnea (>30 breaths/min)
• Hemodynamic instability
• Worsening hypoxemia
• Decreased level of consciousness
• Inability to clear secretions
• Inability to tolerate interface

CPAP/NIV Weaning and Discontinuation

• For CPAP, once FIO2 has been titrated to 50% or less with SPO2 > 93%, with a provider order, CPAP can be slowly titrated.
• For BIPAP, once FIO2 has been titrated, vital signs and PaCO2 values are consistently within normal limits for the patient, with physician’s order, IPAP can be titrated to minimal pressure support level.
• Patient can then be transitioned to nasal O_2.